Here’s the scenario: you have a home PC and the hard drive is running out of free space (again). You don’t know what’s on there – but you suspect that the kids have been downloading videos from their phones and YouTube etc, etc – but you can’t instantly see where all these videos are in order to delete them (as Dad’s we need to get our own back sometimes …..).
Step forward WinDirStat by an unassuming guy called 
Oliver Schneider who, building on the work of some other clever folk, has managed to find a way of both visualising the contents of a hard drive – while at the same time providing a way to quickly identify what files are what.
You really need to download WinDirStat to see what I am wittering on about, but once it has run on a specific folder or entire drive (can take a while depending on the size of the drive) you can click on the representation of large files – and it will tell you precisely which files they are. Conversely, if you you want to know how much space your .avi files are taking up – just select the file type .avi and WinDirStat will outline all the .avi files.
What Oliver doesn’t mention, but is a real cool facility for System Administrators, is the ability to click on a file and automatically send an email to the owner telling them what the file is, the file size – complete with pre-configured text of your choice telling them to delete the file etc.
Really useful stuff that I bump into..... 